ZFS - moving from a zraid1 to zraid2 pool with 1.5tb disks

[Artem Belevich]

On Wed, Jan 5, 2011 at 1:55 PM, Damien Fleuriot <ml at my.gd> wrote:
> Well actually...
>
> raidz2:
> - 7x 1.5 tb = 10.5tb
> - 2 parity drives
>
> raidz1:
> - 3x 1.5 tb = 4.5 tb
> - 4x 1.5 tb = 6 tb , total 10.5tb
> - 2 parity drives in split thus different raidz1 arrays
>
> So really, in both cases 2 different parity drives and same storage...

In second case you get better performance, but lose some data
protection. It's still raidz1 and you can't guarantee functionality in
all cases of two drives failing. If two drives fail in the same vdev,
your entire pool will be gone.  Granted, it's better than single-vdev
raidz1, but it's *not* as good as raidz2.

--Artem